Several methods exist to generate low frequency system reference clocks. Currently the most common uses a crystal-based oscillator utilizing quartz for the crystal element. Crystal oscillators can be temperature compensated. The fundamental resonant frequency of the crystal typically ranges from below 10 MHz up to perhaps 70 MHz. This tone is then used in a phase lock loop to control a higher frequency voltage controlled oscillator that generates the desired frequency of operation of the system. The temperature controlled crystal oscillator typically costs between $0.30 and $1.00 depending upon performance requirements and is considered a commodity in many markets with manufacturers competing primarily on price.
In addition to the cost impact, a crystal oscillator is slow to start, as the crystal itself must go through many periods before there is sufficient energy to support the oscillation. This start up time is inefficient as the radio cannot function until it is done.